package com.maxflow;
import java.io.BufferedInputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;
import java.util.Scanner;
import java.util.regex.Pattern;

public final class In {

	private Scanner scanner;

	/*** begin: section (1 of 2) of code duplicated from In to StdIn */

	// assume Unicode UTF-8 encoding
	private static final String charsetName = "UTF-8";

	// assume language = English, country = US for consistency with System.out.
	private static final java.util.Locale usLocale = new java.util.Locale("en",
			"US");

	// the default token separator; we maintain the invariant that this value
	// is held by the scanner's delimiter between calls
	private static final Pattern WHITESPACE_PATTERN = Pattern
			.compile("\\p{javaWhitespace}+");

	// makes whitespace characters significant
	private static final Pattern EMPTY_PATTERN = Pattern.compile("");

	// used to read the entire input. source:
	// http://weblogs.java.net/blog/pat/archive/2004/10/stupid_scanner_1.html
	private static final Pattern EVERYTHING_PATTERN = Pattern.compile("\\A");

	/*** end: section (1 of 2) of code duplicated from In to StdIn */

	/**
	 * Create an input stream from standard input.
	 */
	public In() {
		scanner = new Scanner(new BufferedInputStream(System.in), charsetName);
		scanner.useLocale(usLocale);
	}

	/**
	 * Create an input stream from a socket.
	 */
	public In(java.net.Socket socket) {
		try {
			InputStream is = socket.getInputStream();
			scanner = new Scanner(new BufferedInputStream(is), charsetName);
			scanner.useLocale(usLocale);
		} catch (IOException ioe) {
			System.err.println("Could not open " + socket);
		}
	}

	/**
	 * Create an input stream from a URL.
	 */
	public In(URL url) {
		try {
			URLConnection site = url.openConnection();
			InputStream is = site.getInputStream();
			scanner = new Scanner(new BufferedInputStream(is), charsetName);
			scanner.useLocale(usLocale);
		} catch (IOException ioe) {
			System.err.println("Could not open " + url);
		}
	}

	/**
	 * Create an input stream from a file.
	 */
	public In(File file) {
		try {
			scanner = new Scanner(file, charsetName);
			scanner.useLocale(usLocale);
		} catch (IOException ioe) {
			System.err.println("Could not open " + file);
		}
	}

	/**
	 * Create an input stream from a filename or web page name.
	 */
	public In(String s) {
		try {
			// first try to read file from local file system
			File file = new File(s);
			if (file.exists()) {
				scanner = new Scanner(file, charsetName);
				scanner.useLocale(usLocale);
				return;
			}

			// next try for files included in jar
			URL url = getClass().getResource(s);

			// or URL from web
			if (url == null) {
				url = new URL(s);
			}

			URLConnection site = url.openConnection();
			InputStream is = site.getInputStream();
			scanner = new Scanner(new BufferedInputStream(is), charsetName);
			scanner.useLocale(usLocale);
		} catch (IOException ioe) {
			System.err.println("Could not open " + s);
		}
	}

	/**
	 * Create an input stream from a given Scanner source; use with
	 * <tt>new Scanner(String)</tt> to read from a string.
	 * <p>
	 * Note that this does not create a defensive copy, so the scanner will be
	 * mutated as you read on.
	 */
	public In(Scanner scanner) {
		this.scanner = scanner;
	}

	/**
	 * Does the input stream exist?
	 */
	public boolean exists() {
		return scanner != null;
	}

	/***
	 * begin: section (2 of 2) of code duplicated from In to StdIn, with all
	 * methods changed from "public" to "public static"
	 ***/

	/**
	 * Is the input empty (except possibly for whitespace)? Use this to know
	 * whether the next call to {@link #readString()}, {@link #readDouble()},
	 * etc will succeed.
	 */
	public boolean isEmpty() {
		return !scanner.hasNext();
	}

	/**
	 * Does the input have a next line? Use this to know whether the next call
	 * to {@link #readLine()} will succeed.
	 * <p>
	 * Functionally equivalent to {@link #hasNextChar()}.
	 */
	public boolean hasNextLine() {
		return scanner.hasNextLine();
	}

	/**
	 * Is the input empty (including whitespace)? Use this to know whether the
	 * next call to {@link #readChar()} will succeed.
	 * <p>
	 * Functionally equivalent to {@link #hasNextLine()}.
	 */
	public boolean hasNextChar() {
		scanner.useDelimiter(EMPTY_PATTERN);
		boolean result = scanner.hasNext();
		scanner.useDelimiter(WHITESPACE_PATTERN);
		return result;
	}

	/**
	 * Read and return the next line.
	 */
	public String readLine() {
		String line;
		try {
			line = scanner.nextLine();
		} catch (Exception e) {
			line = null;
		}
		return line;
	}

	/**
	 * Read and return the next character.
	 */
	public char readChar() {
		scanner.useDelimiter(EMPTY_PATTERN);
		String ch = scanner.next();
		assert (ch.length() == 1) : "Internal (Std)In.readChar() error!"
				+ " Please contact the authors.";
		scanner.useDelimiter(WHITESPACE_PATTERN);
		return ch.charAt(0);
	}

	/**
	 * Read and return the remainder of the input as a string.
	 */
	public String readAll() {
		if (!scanner.hasNextLine())
			return "";

		String result = scanner.useDelimiter(EVERYTHING_PATTERN).next();
		// not that important to reset delimeter, since now scanner is empty
		scanner.useDelimiter(WHITESPACE_PATTERN); // but let's do it anyway
		return result;
	}

	/**
	 * Read and return the next string.
	 */
	public String readString() {
		return scanner.next();
	}

	/**
	 * Read and return the next int.
	 */
	public int readInt() {
		return scanner.nextInt();
	}

	/**
	 * Read and return the next double.
	 */
	public double readDouble() {
		return scanner.nextDouble();
	}

	/**
	 * Read and return the next float.
	 */
	public float readFloat() {
		return scanner.nextFloat();
	}

	/**
	 * Read and return the next long.
	 */
	public long readLong() {
		return scanner.nextLong();
	}

	/**
	 * Read and return the next short.
	 */
	public short readShort() {
		return scanner.nextShort();
	}

	/**
	 * Read and return the next byte.
	 */
	public byte readByte() {
		return scanner.nextByte();
	}

	/**
	 * Read and return the next boolean, allowing case-insensitive "true" or "1"
	 * for true, and "false" or "0" for false.
	 */
	public boolean readBoolean() {
		String s = readString();
		if (s.equalsIgnoreCase("true"))
			return true;
		if (s.equalsIgnoreCase("false"))
			return false;
		if (s.equals("1"))
			return true;
		if (s.equals("0"))
			return false;
		throw new java.util.InputMismatchException();
	}

	/**
	 * Read all strings until the end of input is reached, and return them.
	 */
	public String[] readAllStrings() {
		// we could use readAll.trim().split(), but that's not consistent
		// since trim() uses characters 0x00..0x20 as whitespace
		String[] tokens = WHITESPACE_PATTERN.split(readAll());
		if (tokens.length == 0 || tokens[0].length() > 0)
			return tokens;
		String[] decapitokens = new String[tokens.length - 1];
		for (int i = 0; i < tokens.length - 1; i++)
			decapitokens[i] = tokens[i + 1];
		return decapitokens;
	}

	/**
	 * Read all ints until the end of input is reached, and return them.
	 */
	public int[] readAllInts() {
		String[] fields = readAllStrings();
		int[] vals = new int[fields.length];
		for (int i = 0; i < fields.length; i++)
			vals[i] = Integer.parseInt(fields[i]);
		return vals;
	}

	/**
	 * Read all doubles until the end of input is reached, and return them.
	 */
	public double[] readAllDoubles() {
		String[] fields = readAllStrings();
		double[] vals = new double[fields.length];
		for (int i = 0; i < fields.length; i++)
			vals[i] = Double.parseDouble(fields[i]);
		return vals;
	}

	/*** end: section (2 of 2) of code duplicated from In to StdIn */

	/**
	 * Close the input stream.
	 */
	public void close() {
		scanner.close();
	}

	/**
	 * Reads all ints from a file
	 * 
	 * @deprecated Clearer to use <tt>new In(filename)</tt>.
	 *             {@link #readAllInts()}
	 */
	public static int[] readInts(String filename) {
		return new In(filename).readAllInts();
	}

	/**
	 * Reads all doubles from a file
	 * 
	 * @deprecated Clearer to use <tt>new In(filename)</tt>.
	 *             {@link #readAllDoubles()}
	 */
	public static double[] readDoubles(String filename) {
		return new In(filename).readAllDoubles();
	}

	/**
	 * Reads all strings from a file
	 * 
	 * @deprecated Clearer to use <tt>new In(filename)</tt>.
	 *             {@link #readAllStrings()}
	 */
	public static String[] readStrings(String filename) {
		return new In(filename).readAllStrings();
	}

	/**
	 * Reads all ints from stdin
	 * 
	 * @deprecated Clearer to use {@link StdIn#readAllInts()}
	 */
	public static int[] readInts() {
		return new In().readAllInts();
	}

	/**
	 * Reads all doubles from stdin
	 * 
	 * @deprecated Clearer to use {@link StdIn#readAllDoubles()}
	 */
	public static double[] readDoubles() {
		return new In().readAllDoubles();
	}

	/**
	 * Reads all strings from stdin
	 * 
	 * @deprecated Clearer to use {@link StdIn#readAllStrings()}
	 */
	public static String[] readStrings() {
		return new In().readAllStrings();
	}

	/**
	 * Test client.
	 */
	public static void main(String[] args) {
		In in;
		String urlName = "http://introcs.cs.princeton.edu/stdlib/InTest.txt";

		// read from a URL
		System.out.println("readAll() from URL " + urlName);
		System.out
				.println("---------------------------------------------------------------------------");
		try {
			in = new In(urlName);
			System.out.println(in.readAll());
		} catch (Exception e) {
			System.out.println(e);
		}
		System.out.println();

		// read one line at a time from URL
		System.out.println("readLine() from URL " + urlName);
		System.out
				.println("---------------------------------------------------------------------------");
		try {
			in = new In(urlName);
			while (!in.isEmpty()) {
				String s = in.readLine();
				System.out.println(s);
			}
		} catch (Exception e) {
			System.out.println(e);
		}
		System.out.println();

		// read one string at a time from URL
		System.out.println("readString() from URL " + urlName);
		System.out
				.println("---------------------------------------------------------------------------");
		try {
			in = new In(urlName);
			while (!in.isEmpty()) {
				String s = in.readString();
				System.out.println(s);
			}
		} catch (Exception e) {
			System.out.println(e);
		}
		System.out.println();

		// read one line at a time from file in current directory
		System.out.println("readLine() from current directory");
		System.out
				.println("---------------------------------------------------------------------------");
		try {
			in = new In("./InTest.txt");
			while (!in.isEmpty()) {
				String s = in.readLine();
				System.out.println(s);
			}
		} catch (Exception e) {
			System.out.println(e);
		}
		System.out.println();

		// read one line at a time from file using relative path
		System.out.println("readLine() from relative path");
		System.out
				.println("---------------------------------------------------------------------------");
		try {
			in = new In("../stdlib/InTest.txt");
			while (!in.isEmpty()) {
				String s = in.readLine();
				System.out.println(s);
			}
		} catch (Exception e) {
			System.out.println(e);
		}
		System.out.println();

		// read one char at a time
		System.out.println("readChar() from file");
		System.out
				.println("---------------------------------------------------------------------------");
		try {
			in = new In("InTest.txt");
			while (!in.isEmpty()) {
				char c = in.readChar();
				System.out.print(c);
			}
		} catch (Exception e) {
			System.out.println(e);
		}
		System.out.println();
		System.out.println();

		// read one line at a time from absolute OS X / Linux path
		System.out.println("readLine() from absolute OS X / Linux path");
		System.out
				.println("---------------------------------------------------------------------------");
		in = new In("/n/fs/introcs/www/java/stdlib/InTest.txt");
		try {
			while (!in.isEmpty()) {
				String s = in.readLine();
				System.out.println(s);
			}
		} catch (Exception e) {
			System.out.println(e);
		}
		System.out.println();

		// read one line at a time from absolute Windows path
		System.out.println("readLine() from absolute Windows path");
		System.out
				.println("---------------------------------------------------------------------------");
		try {
			in = new In("G:\\www\\introcs\\stdlib\\InTest.txt");
			while (!in.isEmpty()) {
				String s = in.readLine();
				System.out.println(s);
			}
			System.out.println();
		} catch (Exception e) {
			System.out.println(e);
		}
		System.out.println();

	}

}